This invention relates to the art of sampling fluids for selected components, such as contaminants or pollutants, and has particular relationship to such sampling in whose practice the content of the components in the fluid is to be precisely determined. In the interest of facilitating the understanding of this invention, the invention is herein described as applied to concrete situations: the protection of industrial workers against chemicals such as vinyl chloride and the others listed in Guild U.S. Pat. No. 3,870,492, particularly as required by the Occupational Safety and Health Act (OSHA -- Act 91-596) and the carrying out of air pollution studies. In following this practice, it is not intended in any way to restrict the scope of this invention.
In the area of Industrial Hygiene described above and in certain air pollution studies, it is necessary to repeatedly collect air samples of relatively low volume over long time periods. Typically, in an industrial plant, a worker may, during the time that he is in the plant, which may be 6 or 8 hours or longer, repeatedly collect samples of 1 milliliter to 200 milliliters per minute of the air which he breathes. The collection must be effected with apparatus, operating accurately, and typically including a pump unit and an adsorbent. The worker must be capable of carrying this apparatus continuously while in the plant. This apparatus must be automatically operable without attention from the worker while he attends to his assigned duties and indeed without the worker having to be conscious as to its operation.
It is accordingly an object of this invention to meet the above conditions and to provide apparatus of light weight capable of being carried, with the same absence of attention as he wears an article of clothing, by personnel in a region under observation during long periods of time, and which apparatus shall be capable of operating efficiently and accurately without attention of the personnel carrying the apparatus to collect selected pollutants from samples of repeated low-volume flow of the air in the region.
It is another object of this invention to provide such apparatus including a pump and valves which shall be driven from a low-power rechargeable battery with a minimal drain on the battery and in whose operation the air leakage from the pump and valves shall be minimized.